The present invention relates to high intensity discharge (H.I.D.) lighting fixtures and in particular to an improved configuration for the components of such fixtures.
High intensity discharge light fixtures of the type utilizing high pressure sodium, metal halide or mercury lamps generate considerable heat when in use. Such fixtures are commonly used in exterior environment such as parking lots, sports arenas, for public lighting and the like. As a result, the fixtures must be built to withstand severe weather conditions and particularly to protect the lamp from rain and snow. One obvious way to protect the lamp is to seal the fixture components so as to make them water tight. However, by making the fixtures water tight heat generated by the lamp is trapped within the fixture. That is, the gaskets used to make the fixture water tight also serve as barriers to the flow of cooling air for the lamp. As a result, the fixture tends to run hot and must be designed with a sufficiently enlarged lamp area to permit the lamp heat to be disipated through conduction. This results in an increased use of material plus an enlarged fixture. In addition, the intense heat generated within the lamp housing tends to produce a vacuum condition which draws humid air and dirt particles into the fixture through any leak in the seal that may eventually occur. Thus, the sealed fixture of the prior art tends to defeat its own principal purpose in time.
In view of the above, it is the principal object of the present invention to provide an improved high intensity discharge light fixture which permits a free flow of air into the fixture interior while still protecting the fixture from water.
A further object is to provide such a fixture which eliminates the need for gaskets at the interface between fixture components.
A still further object is to provide such a fixture which may operate with a conventional high intensity discharge lamp.
Still another object is to provide such a fixture wherein the size of the lamp compartment and other components may be minimized.
Still other objects and advantages will be apparent from the following description of the present fixture.